Dinosaurs are the general name for reptiles on the earth10.3 billion years ago. There are many kinds of them, and their size, shape and living habits are different. Land, sea and sky are all sites of dinosaurs and reptiles. As big as Mamen Xilong found in Hechuan County, Sichuan Province, China, it is 22 meters long, 3.5 meters high and weighs 40-50 tons. Usually living in a lake with a water depth of 5 ~ 10 meters, using the buoyancy of water to float the heavy body and feed on algae in the water. The whole body of the parrot dragon is only the size of a puppy. Some can fly in the air, such as long-tailed beak dragon, with sharp teeth and long tail. At the end of the tail, there is a membrane shaped like a fly swatter, and the flying tool is the wing membrane. Some are overlords in the sea, such as Himalayan ichthyosaurs, which eat meat and are good at swimming. Its upper and lower jaws are particularly long, forming a long kiss, with teeth in its mouth, and its shape is very similar to that of dolphins today. Some warriors on land, such as Stegosaurus, were 6 meters long, with small heads and high arches on their backs. There are two rows of upright triangular bone plates with bone spurs at the tip of the tail, which are weapons against the enemy. By about10.3 billion years ago, the dinosaurs that ruled for a period of time were completely extinct on the earth due to the changes of topography and climate caused by strong crustal movement. The reason for the extinction of dinosaurs is still inconclusive, but it should be noted that the reasons are various and complicated, which is the result of the interaction between the external environment changes and the internal factors of dinosaurs at that time.